Auger-bit.



L E. DOLDT.

AUGER BIT.

APPLICATION FILED FEB. 2, I916- Patented Oct. 30, 1917.

JOHN E. norm, vor ronrnann, MAINE.

AUGER-BIT.

Specification of Letters Patent.

Patented Got. 30, 1917.

Application filed February 2, 1916. Serial No. 75,656.

To all whom it may camera:

Be it known that I, JOHN. E. Donor, a citizen of the United States, residing at Portland, in the county of Cumberland and State of Maine, have invented certain new and useful Improvements in Auger-Bits; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same. v

This invention relates to anger bits and more particularly to combined wood boring and routing bits.

The pitch of the. spiral at the cutting lips in the usual form of auger bit is about 35 to the axis of the bit. In order to obtain this pitch at the cutting lips, the entire spiral of the bit has a uniform pitch of approximately 35". While boring with this type of bit, the chips as they are formed at the cutting lips are forced out against the face of the spiral which forms the chip gutter, and since the face of the spiral has a comparatively low pitch, it offers an effective frictional resistance to the movev ment of the chips along the gutter causing them to pack tightly therein and form a wad, which must be forced along the gutter by the lifting whatever slight conveying action the spiral gutter may have due to the packing of the chips tightly against the inner surface of the whole. This interferes with the boring action of the cutting head, impairing its efficiency and increasing the strain on the bit and the force required to operate it.

The primary object of the present invention is to provide a boring bit which will overcome the objections noted above and which will have an efficient boring action and readily remove the chips. M I

In accordance with this object one feature of the invention contemplates formingthe spiral body portion of the bit of two contiguous sections, the lower cutting section having a comparatively slight pitch to provide an effective cutting angle at the cutting lips, and the upper chip-clearing section having a comparatively steep pitch to form a chip gutter into ,and throughwhich the chips may move freely longitudinally of the bit, the pitch of the lower section being abruptly merged into the pitch of the upper section. The low pitch of the cutting section extends back from the cutting lips suffipower of the cutting lips andciently far to get an efficient low pitch cutting and lifting wedge, and is then abruptly or rapidly increased to the steep pitch of the chip-clearing section to immediately enlarge the chip gutter. The chips as they are formed by the low pitch cutting lips pass into the comparatively large chip gutter,

which is of such a steep pitch that the fric-,

tional resistance offered to the travel of the chips 13 not suficient to cause them to pack and form a wad. The chips therefore move freely through the large chip gutter without interfering with the efficient and rapid action of the cutting lips or materially increasing the strain on the bit or the force required to operate it. In fact, when boring upwardly, the steep pitch of the chip gutter may allow the chips to fall by gravity away from the cutting lips and out of the hole.

In the illustrated embodiment of the invention the low pitch of the cutting head extends back from the cutting lips a dis tance about equal to the length of the chip formed, but this length of low pitch is not necessarily fixed, since the low pitch may extend back farther for some classes of work before being abruptly expanded into the steep pitch of the clearing section and still avoid the wadding of chips. 7 7

Another object of the invention is to so construct a boring bit that it will be well adapted for routing.

In accordance with this object another feature of the invention contemplates the pro- With these objects in view, the invention consists in the improved boring bit herein-,

after described and set forth in the claims.

The several features of the invention are illustrated in the accompanying drawings, in which Figure 1 is a view in side elevation of my improved boring bit Fig. 2 is a horizontal section of the spiral body of the bit taken on the line 2 2 of Fig. 1; and

The boring bit shown 'in'the drawings consists of a spiral body portion 10 llfiV-lllg a lead screw 12 at its lower end and a shank l l at its upper end. Onthe cutting end of thespira'l bodyportion' at each side'of the lead screw are formed a spur lip. 16 andn cutting lip 18. The cutting lips are formed amhe end of the spir'al body POE-1011* and have-their cutting edges substanti'allyjat right-angles to theaXiscf the bit. The

formation of the cutting lips, however, may be varied in getting (BfiGCtlYQ results?- To secure a more'efi'e'ctiye boring bity the spiral bOCl5 '10 OO11S1StS of twosections. The

lowersection or cutting head- 20 star-teat the cutting lips and -extendsf back a short distance on the spiral. Tliepitch orin clinationof the section 20 is comparatively slight; so thatthe cut-ting lips are given an effective cutting angle. This pitch is pref erably slightly greater thaiuthe pitch of the thread on the lead screw 12; so-thatit will tend'to force the lead screw into the wood: The upper, or chip-clearingsection east the spiral body continues from thecutting section -20 to the-slianklat; This section has a comparatively steep inclination or pitch, which provides a large helical groove orchip gutter to receive the-chips asthey jare foi ced along from the cuttinghea'di Thecross-sectional area of thehelical groove oft'he cutting section is much less thairthe area of thehelical groove of the chip-clearingsection, so that, as the chips are 'forced up the spiral bygthe lowpitch Wedge of the cutting section, they expandan'ch'become freely inovable'dnthe chipclearinig section. l Thelarge area ofthe chip gutter in the section 22 allows'thechipszto loosely 'I11OV"alOl1g"iJl1 gutter, so thatthe iriction oi' the chips between the 'it'ace of thegutter and the surface of the hole is very slight; The most ettectivo angle-for cutting 'diflerent kinds of wood can be formed in the cutting section, and the chips when "out are advanced to a spiral" with steep" pitch, which foi'ms a gutter'ofsufiicient size to take care of the chips no matter how fast-they are formed;

The steep "spiral along the chip-clearing section also permits the formation" of chip gutters of adequate area to handle the chips; in which the l wall or web between the gutters is much thicker than would be practical iii-bits having gutters of slight l uniitorm pitchb The thick wall of thespiralincreasesth'e strength" of the bit so th'atit willbe betteradapted to resist the heavy torsional strains which are liable to temporarily disto'rt bits' of the usualconstruction and cause themto bind-in a hole or break.

To equip the bit for routii'ig, thelead-ing corners ottheedges of the spiral-body POJP l paratively sharp and extend approximately to the edge of the hole. The edges Z lfOrni continuously"acting: cutting edges when routing, and since they are formed on a spiral having a comparatively steep pitcln an efiectiye shearcut;will be -macle. -While boring a hole, then-outing taces 2-l will keep the bit centered and form a smootli -true= hole; -Tlie"corners 2-8 aid tlie -routingfaces 24. in- -holding the hit centered inthe hole; 1

and i when the bitis reverse d in remoyin g lt'ltrom =th'e hol'e,the corners '28 prevent chi-ps- 1 front becoming--wedged= between the 7 faceofthehole and t he edge' of the sgiiah Vi hen boring with any type of bit 'which isnot- =prop 'lv centered inthe chuck --or bitstoclnthe lead' sci'ewa ill ho'ld the cut ting end of the bit centered; causing the bit to wahble." This wabbling action places a great-strainon the spiral; which 'acts to' crystallize the inaterial so that 1 the bit will soon-break. In boring with a bithaving a routing edgeon-its spiral -body;. tl1e rou ing edg'e will gradually cut away the walls of the hole to enlargedt, asthe -bit-wau so th'a't the re will be yerylittle strain on the spiral.

Thelead screw 12 shown in Fig;% is proe'. videdwith a thread-orfin O'whi'chhas' a special construct-ion for rapid and-eflicient boring Itwill be noted that r the uppersurtace" of the is flat iwhile" the" lower surface is reinforced or bridged to the body of thescrew.- Witlr this construoticm a comparatively thin: fin can be foimed which will easily one its way into the WOOtlia The reiniorcin g en the lower edge of the fiirfurther"prevents thetin fI'OHI bBl'HQ' stripped off-"of the screw when i the tool is being used for routing;

\Vhile thein entiionfhas been shown and described-as embodied in a bithaving a lead screWat-its cuttingend, it' will be under stood that the broader "features of the -in"- venti-on may be embodied with equal ad vantage in mill bitswhich 'donot have-lead screws;

Tliesh'anlt 145 shown in the drawings is that used in a common type of boring ma chine; but I this shank may be shaped to adapt it to fit'any suitable-type of chuck or bitstoclc Hayingthiis described my invention, what is claimed asneW; is

1. A boring bitcomprising a spiralbo'dy portion fornied in two contiguous sections, the lower cutting section having a slight pitch toprovide .an effective cutting angle at the cutting lips, and the upper chipclearing" section having a comparatively steep pitch to form a chip gutter into and through which the chips may move freely longitudinally of the bit, the pitch of the lower section being bruptly merged into the pitch of the upper section.

2. A boring bit comprising a spiral body portion formed in two contiguous sections, the lower cutting section having a slight pitch to provide an efiective cutting angle at the cutting lips, and the upper chipclearing section having a comparatively steep pitch to form a chip gutter into and through which the chips may move freely longitudinally of the bit, the lower section being abruptly merged into the pitch of the upper section, and the lead ing corners of the spiral edges being provided with a clearance to form cutting edges for routing.

3. A boring bit comprising a double spiral body portion terminating in oppositely disposed cutting lips, and a lead screw on the body portion between the lips, the edges of the spirals being shaped so that only the corners make point contacts with the face of the hole being bored, the leading corner being a cutting edge for routing.

4. A boring bit comprising a body por- Copies of this patent may be obtained for pitch of the Y tion formed in two spiral sections and a shank, the lower section of the body portion consisting of a short cutting head the spiral portion of which has a pitch" less than 45 with the axis of the bit, and an upper chipclearing section, the spiral portion of which has a pitch greater than 45 with the axis of the bit.

5; A boring bit comprising a double spiral body portion formed in two sections, the lower cutting section having a slight pitch extending only a fraction of the distance around the bit, the upper chip clearing section having a steep substantially uniform pitch extending from the end of the cutting section to the shank of the bit. I

6. A boring bit comprising a double spiral body portion and a shank, the body portion consisting of a short cutting head having cutting lips and a chip-clearing section extending from the shank to the cutting head, the pitch of the spiral of the cutting head being comparatively slight, and the pitch of the chip-clearing section being comparatively steep, the pitch of the spiral of the cutting head being abruptly merged into the pitch of the chip-clearing section.

JOHN E. DOLDT.

five cents each, by addressing the Commissioner of Patents,

Washington, D. 0. 

